1. Field of the Invention
The present invention relates to a tool adapter for mounting a tool on a robot wrist. The present invention also relates to a robot with a tool adapter attached to a wrist.
2. Description of the Related Art
Generally, the wrist of an industrial robot (in this specification, simply called a robot) has two or three degrees of freedom. In certain cases, when mounting the wrist with a tool (i.e., an end effector), such as a stud welding gun or a boring head, that receives a relatively large reaction force from an object being worked on, the direction of the reaction force expected to be applied to the wrist through the tool from the object has to be taken into account. For example, a tool supporting device disclosed in Japanese Unexamined Patent Publication No. H07-001276 (JPH07-001276A) is configured to mount a tool to an arm end of a multi-axis robot in a swingable manner and in a gravitationally balanced condition, and includes a pressing device for pressing the mounted tool onto the workpiece. Referring to the drawing, it will be understood that the “end of a robot arm Ra” is connected to the “robot arm Ra” so as to be rotatable about a first axis (the axis perpendicular to the plane of the page) and that a “support bracket 10 attached to the end of the robot arm Ra” is connected to the “end of the robot arm Ra” so as to be rotatable about a second axis orthogonal to the first axis. Further, referring to the drawing, it will also be understood that the vector of the reaction force applied to the tool from the workpiece being worked on is located in a position that is displaced substantially parallel from the second axis contained in the “support bracket 10” and that does not intersect the first axis contained in the “end of the robot arm Ra”.
In the above-described configuration disclosed in JPH07-001276A, a moment of force about the first axis occurs at the “end of the robot arm Ra”, i.e., the wrist, because of the reaction force applied to the tool from the workpiece being worked. If the wrist is deflected due to the moment of force, the quality of the robot operation being performed using the toll may be affected. If, in this case, the position of the vector of the reaction force applied to the tool from the workpiece being worked on is made to coincide with the second axis of the “support bracket 10”, the occurrence of the moment of force can be avoided. This configuration, however, can increase the distance from the first axis of the “end of the robot arm Ra” to the tool end, tending to cause interference with the workpiece and its peripheral objects, and hence a concern that the workability of the operation may degrade.